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bpo-40302: Add pycore_byteswap.h header file (GH-19552)

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Add a new internal pycore_byteswap.h header file with the following
functions:

* _Py_bswap16()
* _Py_bswap32()
* _Py_bswap64()

Use these functions in _ctypes, sha256 and sha512 modules,
and also use in the UTF-32 encoder.

sha256, sha512 and _ctypes modules are now built with the internal
C API.
This commit is contained in:
Victor Stinner 2020-04-17 17:47:20 +02:00 • committed by GitHub
parent 485e715cb1
commit 1ae035b7e8
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13 changed files with 219 additions and 112 deletions
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89
Include/internal/pycore_byteswap.h Normal file
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/* Bytes swap functions, reverse order of bytes:
- _Py_bswap16(uint16_t)
- _Py_bswap32(uint32_t)
- _Py_bswap64(uint64_t)
*/
#ifndef Py_INTERNAL_BSWAP_H
#define Py_INTERNAL_BSWAP_H
#ifdef __cplusplus
extern "C" {
#endif
#ifndef Py_BUILD_CORE
# error "this header requires Py_BUILD_CORE define"
#endif
#if defined(__clang__) || \
(defined(__GNUC__) && \
((__GNUC__ >= 5) || (__GNUC__ == 4) && (__GNUC_MINOR__ >= 8)))
/* __builtin_bswap16() is available since GCC 4.8,
__builtin_bswap32() is available since GCC 4.3,
__builtin_bswap64() is available since GCC 4.3. */
# define _PY_HAVE_BUILTIN_BSWAP
#endif
#ifdef _MSC_VER
/* Get _byteswap_ushort(), _byteswap_ulong(), _byteswap_uint64() */
# include <intrin.h>
#endif
static inline uint16_t
_Py_bswap16(uint16_t word)
{
#ifdef _PY_HAVE_BUILTIN_BSWAP
return __builtin_bswap16(word);
#elif defined(_MSC_VER)
Py_BUILD_ASSERT(sizeof(word) == sizeof(unsigned short));
return _byteswap_ushort(word);
#else
// Portable implementation which doesn't rely on circular bit shift
return ( ((word & UINT16_C(0x00FF)) << 8)
| ((word & UINT16_C(0xFF00)) >> 8));
#endif
}
static inline uint32_t
_Py_bswap32(uint32_t word)
{
#ifdef _PY_HAVE_BUILTIN_BSWAP
return __builtin_bswap32(word);
#elif defined(_MSC_VER)
Py_BUILD_ASSERT(sizeof(word) == sizeof(unsigned long));
return _byteswap_ulong(word);
#else
// Portable implementation which doesn't rely on circular bit shift
return ( ((word & UINT32_C(0x000000FF)) << 24)
| ((word & UINT32_C(0x0000FF00)) << 8)
| ((word & UINT32_C(0x00FF0000)) >> 8)
| ((word & UINT32_C(0xFF000000)) >> 24));
#endif
}
static inline uint64_t
_Py_bswap64(uint64_t word)
{
#ifdef _PY_HAVE_BUILTIN_BSWAP
return __builtin_bswap64(word);
#elif defined(_MSC_VER)
return _byteswap_uint64(word);
#else
// Portable implementation which doesn't rely on circular bit shift
return ( ((word & UINT64_C(0x00000000000000FF)) << 56)
| ((word & UINT64_C(0x000000000000FF00)) << 40)
| ((word & UINT64_C(0x0000000000FF0000)) << 24)
| ((word & UINT64_C(0x00000000FF000000)) << 8)
| ((word & UINT64_C(0x000000FF00000000)) >> 8)
| ((word & UINT64_C(0x0000FF0000000000)) >> 24)
| ((word & UINT64_C(0x00FF000000000000)) >> 40)
| ((word & UINT64_C(0xFF00000000000000)) >> 56));
#endif
}
#ifdef __cplusplus
}
#endif
#endif /* !Py_INTERNAL_BSWAP_H */